Truncated reactive center loop decrease the inhibitory activity of Antheraea pernyi serine protease inhibitor 6

Here, we assessed the effect of a systematic change in reactive center loop (RCL) length, N-terminal to the reactive center, on the inhibitory activity of the recombinant Apserpin-6. The domain prediction results indicated that the RCL is located between the amino acid numbered 359–379 at the C-terminal of Apserpin-6. The N-terminal variable region for amino acid positions P7–P1 of the RCL of Apserpin-6 was truncated or extended by residue deletion or insertion using site-directed mutagenesis. The recombinant Apserpin-6 with one or two residues insertion in RCL had no effect on prophenoloxidase (proPO) activity, whereas deletion of one or two residues in RCL lowered the efficiency of inhibition of Apserpin-6. The results of this study will facilitate the understanding of inhibition mechanism of RCL on proPO activity.     

A novel hexamerin with an unexpected contribution to the prophenoloxidase activation system of the Chinese oak silkworm,Antheraea pernyi

Hexamerin was originally identified as a storage protein but later confirmed to be involved in many physiological processes. In the present study, we cloned and characterized a novel hexamerin complementary DNA sequence from the Chinese oak silkworm, Antheraea pernyi (Ap-hexamerin), which shows high homology with reported insect methionine-rich hexamerins. The tissue distribution and time course of expression demonstrated that Ap-hexamerin was predominantly synthesized in the fat body and the expression level was significantly increased in response to the microbial challenge, suggesting the relevance of Ap-hexamerin to immune responses. In further immune functional studies, Ap-hexamerin was confirmed to take part in the upregulation of prophenoloxidase (PPO) activation in A. pernyi haemolymph triggered by pathogen-associated molecular patterns (PAMPs). Additional molecular interaction analysis revealed that Ap-hexamerin is capable of binding the PAMPs used in the phenoloxidase assay, suggesting hexamerin in A. pernyi may positively regulate haemolymph PPO activation, acting as a pattern recognition protein.     

The electrical and mechanical properties of the proleg retractor muscle of the Chinese oak silkmoth larva

ABSTRACT. The main proleg retractor muscle (y) of Antheraea pernyi Guer. (Lepidoptera, Saturniidae) larvae consists of three layers of fibres. The innermost layer of fibres is dually innervated. Cobalt backfills of the two motor neurones, in nerve 2d, showed the somata to be situated ventrally and anteriorly in the same segmental ganglion, ipsilateral to the filled nerve. Intramuscular microelectrode recordings showed excitatory junction potentials (EJPs) of two distinct amplitudes, both of which were relatively slow. However, 26% of the larger amplitude EJPs had an active membrane response. The EJPs and mechanical responses both summated at low stimulation frequencies. Large EJPs resulted in a much greater development of tension than small ones. Extracellular stimulation of nerve lbiii modulated peak tension and peak rate of relaxation.     

Safety evaluation of four entomopathogenic nematode species against two silkworm species

Chinese oak silkworm (Antheraea pernyi) and mulberry silkworm (Bombyx mori) are economically important insects used for silk production and food resource. Entomopathogenic nematodes (EPNs) from the families of Steinernematidae and Heterorhabditidae are beneficial organisms currently considered in biological control. In this paper, we evaluated survival of two silkworm species exposed to four Steinernema species which are widely applied in pest control. The results showed that among four Steinernema species, S. bicornutum and S. feltiae did not have an effect on the larval survival to the two silkworm species, whereas S. carpocapsae and S. glaseri did have an effect. Each Steinernema species poses no threat to hatchability of eggs, pupation rate, larval durations and cocoon shell ratio.